Air conditioners are devices for cooling and cooling indoor rooms using a cooling cycle including a compressor, a condenser, an expansion device, and an evaporator. During the operation of a cooling cycle of an air conditioner, i.e., during the operation of a compressor, water in the air is condensed on the surface of an evaporator, and thus, compressed water is generated. Then, the compressed water drops below the evaporator. However, if the compressed water freezes up on the surface of the evaporator due to low-temperature air around the evaporator, the performance of the air conditioner may deteriorate due to an unsmooth heat exchange between a coolant and air.
In order to address this, the operation of a compressor may be stopped in the middle of the operation of an air conditioner so that the operation of the air conditioner can also be stopped. Then, a defrost operation may be performed for a predetermined amount of time so that the surface of an evaporator can be defrosted. Once the surface of the evaporator is completely defrosted, the operation of the compressor may be resumed so that the operation of the air conditioner can be resumed.
However, since a defrost operation can be performed only after the operation of an air conditioner is stopped, a cooling function or a heating function cannot be performed during a defrost operation, thereby reducing user convenience.